The large-diameter slewing bearing, turntable bearing or swing ring refers to the large slewing bearing with a diameter of more than 5 meters. They are mostly used at cranes, portal cranes, stationary cranes, ship loading and unloading machines, and Large-scale shore cranes and port cranes. In order to achieve the ideal "100-ton crane", "1000-ton crane" and "10000-ton crane", a series of rigid indexes, such as the bearing load, rotating speed, anti-overturning moment, safety, reliability and stability of the slewing bearing, are important factors to build up the excellent quality, it is also applicable in the repair and maintenance of some large slewing bearings with high value and strict construction period.